Apparatus for bending blanks



J 1954 s. LARKIN APPARATUS FOR BENDING BLANKS Filed Oct. 18. 1950 Fla. L

INVENTOR SAM LARK/N ATTORNEYS Patented June 22, 1954 UNITED STATES PATENT OFFICE APPARATUS FOR BENDING BLANKS Sam Larkin, Pine Blufl, Ark., assignor to Larkin Lectro Products Corporation, Pine Bluff, Ark., a corporation of Arkansas Application October 18, 1950, Serial No. 190,700

2 Claims. 1,

My invention relates to a new and improved machine for cutting planar blanks from a strip or sheet of bendable metal, and bending the planar blanks into angular shape.

The invention is particularly useful in shaping the laminations and the sets of laminations which are shown in my applications Serial No. 149,993, filed in the United States Patent Office on March 16, 1950, now abandoned, and Serial No. 155,728, filed on April 13, 1950, now Patent No. 2,634,321, issued April 7, 1953.

As one embodiment of my invention, I shape a blank which is cut by the improved machine disclosed herein or which is cut or pre-cut or preshaped in any other manner, in order to provide said blank with a planar base and two planar lateral legs which have rounded junctions with said planar base. Said blank is thus finally bent to a final normal shape at which its planar lateral legs are perpendicular to said base.

According to one embodiment, I support the planar base-part of a planar blank which may be supported in a horizontal plane, while the planar leg-parts of said blank, which are the end-parts of said blank, are free to bend relative to said base-part. These leg-parts are then bent downwardly relative to said base-part while said base-part is held stationary, and said leg-parts are thus turned by the bending forces towards each other at the junctions between said basepart and said leg-parts. The leg-parts are thus turned towards each, other in simultaneous and equal bending and turning movements, until said leg-parts temporarily form initial acute angles with the base-part. The resilience of the material of the blank and said acute angles are selected, so that upon the quick release of said leg-parts, they turn away from each other under the resilience of said blank until said leg-parts are parallel to each other and are perpendicular to said base-part in the final normal selected bent shape of the blank. Each finished blank has rounded zones or junctions between its base and lateral legs, and these rounded zones or junctions are of the same curvature in successive blanks, even though successive blanks are of different respective lengths.

Numerous additional features and objects of this invention are explained in the annexed description and diagrammatic drawings.

Fig. 1 is a longitudinal front elevation of the improved machine which can be used to practice the improved method;

Fig. 2 is a top plan view of one of the retainers, showinga part of the bending rod;

Fig. 3 is a longitudinal front elevation which shows a part of one of the bending blocks and its associated bending means; and

Fig. 4 is an end elevation of one of the bending blocks and its associated retainer, also showing a part of the respective bending rod.

The machine has a longitudinal bed-plate I, in which a longitudinal shaft 2 is turnable. For convenience, this shaft 2 is shown in the horizontal position. A gear 3 is fixed to shaft 2. This gear 3 can be turned by conventional drive mechanism D. In operating this machine, the shaft 2 may be turned intermittently in the same direction. During each turning movement of shaft 2, it is turned through the same respective angle.

The shaft 2 has right-hand threads 5 and 4, and left-hand threads la and 5a. The associated right-hand and left-hand threads 3 and 401. have the same pitch. The associated right-hand and left-hand threads 5 and 5a have the same pitch,

which is greater than the pitch of threads 4 and.

4a.. As one example, the common pitch of the relatively high-pitch threads 5 and 5a is 150% of the common pitch of the relatively smallpitch threads 4 and 4a.

The machine has a stop block 6b, which has a vertical and planar stop face 6 and a follower 6a. Said follower Ba detachably engages the thread 5a. Said stop block rib is longitudinally associated with a shearing block l, which has a follower la which detachably engages thread 5a. As one example of the operation of the machine, the shaft 2 is turned intermittently in a succession of angular strokes of equal respective an gles, so that the stop block to and the shearing block 1 are moved intermittently and simultaneously and horizontally towards each other, in a succession of short and equal horizontal and iongitudinal strokes. These directions of the simultaneous horizontal movements of stop-block 53b and of shearing block i, are opposed to the respective directions of horizontal arrow A.

A shearing blade 8 is movable up-and-down relative to shearing block I. A guide G for shearing blade 8 is fixed to block 7, so that the shearing block 1 and the shearing blade 8 are moved longitudinally in unison.

Identical bending blocks 9 and I0 have respective followers 9a and Na, which detachably engage the small-pitch fine threads 5a and t.

Each bending block is and It has a top planar and horizontal supporting face. Each bending block 9 and Hi also has a planar bending face F. These planar bending faces F have respecaosnesa tive rounded and convex zones or junctions H and Ila with'the respective top supporting faces of said bending blocks. These edges H and Ha are transversely disposed. Each planar bending face F forms an acute angle with the top planar and horizontal face of the respective bending block 9 Or it. In this embodiment, said angles are 60. As shownin Fig. 1, these bending faces F are inclined towards each other.

The identical bending blocks 9 and I ii are associated with respective and identical supports ,0! retainers l2 and I4, Each retainer 12 and I4 is fixed to a respective vertical arm H, which is detachably fixed by bolts I8 to the rear planar, vertical and longitudinal wall of the respective bending block. Each retainer 12 and I4 has planar and horizontal top and bottom walls.

Each retainer has a respective longitudinal recess I5. Each recess it has two vertical and 1ongitudinal and planar walls, and a transverse L inner vertical and planar wall. These transverse inner walls are designated by the reference numerals l6 and 16a. These recesses l are longitudinally opposed to each other.

' Identical bending means are associated with each bending block 9 and H). In this embodiment, a supporting pivoted arm i9 is pivoted at 2|) to a lug of the respective retainer B2 or [4. A r espective bending arm 2| is pivoted at 22 to each pivot arm IS. A tension spring 23 urges each bending arm 2| to turn longitudinally towards its respective pivoted arm Hi. This relative turning movement between each pivot arm i9 and its respective bending arm 2i, is limited by a stop Illa, which is fixed to the respective pivot arm iii. A respective roll 24 is turnably connected to the end of each bending arm 2 One method of operating the machine and one embodiment of the method is as follows:

A flat strip Sc of resilient material, such as resilient metal, is inserted longitudinally between the top faces of bending blocks 9 and I0 and the bottom planar and horizontal faces of the retainers |2 and Hi. This strip Sa fits snugly between the top faces of the bending block 9 and. Ill and the bottom faces of the retainers l2 and I4. The left planar and transverse edge of said strip Sa abuts the vertical stop wall t of the stop block 6b. This fiat strip Sa also rests upon the top planar and horizontal face of the shearing block 7. At this time, the shearing blade 8 is'in its upper position, above the strip Sa.

- The rear longitudinal edge of strip Sa may then abut the arms H.

The shearing blade 8 is then lowered, in order to cut a blank S of selected length from the strip Sa, while the strip Sa is held stationary.

At this time, the junctions H and Ha are equally longitudinally spaced from the stop face 6 and from the proximate edge of the shearing block '5, so that the flat, severed blank 8 hasa base-part which is supported on the top faces of the bending blocks 9 and it, and said flat blank S'has longitudinal legs W of equal length, which extend oppositely from said horizontal base-part of the blank.

The pivoted arms l9 are now turned downwardly, so that the transverse rolls 24 are moved downwardly to contact with the top face of the blank and said rolls 24 are moved additionally downwardly in order to bend the blank S at the junctions [l and Na. When a bending roll 25 is moved down until it merely touches the top surface of the blank S, prior to bending the blank S, a part of said roll 24 preferably overlies the 4 top surface of the respective bending block 9 oi IE}, and said overlying part of each roll 24 is located in the respective recess l5, whose width exceeds the length of roll 24, as measured in a direction transverse to the plane of Fig. 1. Each roll 24 may then be closer to the respective junction II or i la, than as illustrated in Fig. 3.

The downward thrust on each roll 24 causes it to move longitudinally away from its respective pivot 26, thus increasing the angle between the respective arms i9 and 2|, increasing the tension of the respective spring 2|, and moving the respective arm 2| away from the respective stop 19a. To facilitate this, the minimum angle between arms l9 and 2! may be greater than as shown in Fig. 3, and the axis of rotation of roll 2 3 may be initially to the right of its position shown in Fig. 3, when roll 24 touches the top surface of the blank S, prior to bending the blank S at the junctions I! and Ha. The same applies to the bending means associated with bendin block 9.

When the bending rolls 24 are forced below their initial contact positions shown in Fig. 3, each bending roll 25 bends each leg W of the blank and presses each leg W against a respective bending face F, by a wiping movement which shifts the point of application of each bending force in a direction away from the junction between the base cf blank S and its respective leg W, towards the end of said leg W. The tension of spring 23 supplies and regulates the bending force and the pressure of the respective leg W against the respective bending face F.

Each arm 2| moves freely through the respective recess i5, during the respective bending stroke.

Both bending mechanisms are preferably actuated equally and simultaneously, so that the two bending forces are equal and simultaneously applied, and their lines of application are always longitudinally alined.

The legs W are thus bent initially towards each other as shown in 1, until their respective initial angles with the base of the blank S are 60.

The base of blank S, which rests on the top faces of the bending blocks 9 and H3, is held stationary during the entire bending operation, and also while the pivoted arms i9 are turned upwardly in their release strokes.

The rolls 24 may be moved downwardly along the legs W through any selected distance'during the application of the bending forces.

If the machine is operated without a blank therein, each pair of arms [9 and 2| are movable to an initial position in which the angle between said arms l9 and 2| is determined by stop Mia, and the pressure-roll 24 then abuts the respective supporting face of the respective bending block. In such initial position, the pressureroll 24 is only partially alined with the respective supporting face, and further actuation of arm l9 towards the supporting face causes the roll 24 to ride off the respective supporting face and to roll along the respective face F. The rolls 24 are preferred wiping pressure members, but they may be omitted by providing arms 2| with cam ends which will similarly ride oif the topsupporting surfaces of blocks 9 and I0.

The rolls 24 are preferably wider than the blank Sa. 7 c

The arms l9 may be given a quick downward bending stroke, followed immediately by a quick upward release stroke in which'the rolls 24 are moved out of contact with the bent legs W, either 5., to the position shown in Fig. 3 or above said position.

Upon being released from the bending pressure of rolls 2!, the resilience of the material of the blanks causes said legs W to turn away from each othenat the junctions between said legs and the base-part of the blank, while said basepart is held stationary, thus increasing the angle between each leg and said base-part from the original selected angle to a greater final angle. This final angle may be 90".

When an arm 19 is turned downwardly from its initial position'of Fig. 3, therespective turnable roll 24 is initially pressed downwardly. This initial downward pressure in said roll 24 causes said roll 24 initially to move longitudinally away from the respective pivot 20, thus increasing the angle between the respective arms 19 and 2| against the increased tension of the respective tension spring 23. The respective roll 24 then moves downwardly following the contour of the respective transverse convex edge I I or Ila, thus bending the respective part of the cut strip S into conformity with the respective rounded edge II or Ila. The further downward turning movement of arm l9 causes the respective roller 24 to push the respective leg W into contact with the respective face F, with a pressure which is determined by the tension of spring 23. Hence, when arm I9 is moved back to its initial position of Fig. 3, the 60 angle between the base of the cut strip S and each leg W which is shown in Fig. 1, is enlarged to a 90 angle.

The bent blank is removed from the bending blocks and the shaft 2 is turned through a selected angle so as to move the bending blocks 9 and I longitudinally towards each other and also to move the stop block 6b and the shearing block 1 longitudinally towards each other.

The above operations are repeated, in order to out a second planar blank which is shorter than the first planar blank, and to provide the second bent blank with legs which are shorter than the legs of the first bent blank.

Each bent blank has a rounded junction between its base-part and its legs, and these junctions are of the same shape or substantially the same shape, in the successively bent blanks.

Of course, the machine can be operated by turning the shaft 2 so as to make each blank longer than the next preceding blank. However, it is preferred successively to decrease the lengths of the blanks, in order to produce a set of blanks as shown in Fig. 5 of application Serial No. 149,993, filed on March 16, 1950.

Thus, as one example, the strip So may be of silicon steel, of the type used in making the laminations of the cores of transformers, and said strip Sd may have a thickness of 0.014 inch.

The first rectangular blank may be cut to a length of 9 inches, and be bent to provide a rectangular base or base-part whose length is 5 inches, with two equal and rectangular legs which are perpendicular to said base, so that the height of each leg is 2 inches.

The next blank may be cut to a length of 8.958 inches, and bent to provide a base whose length is 4.972 inches, with two legs, each said leg having a length of 1.993 inches.

In making the second blank, the stop block 6?) and the shearing block 1 are moved longitudinally towards each other through a total distance of 0.042 inch, which is 300% of the thickness of the strip Sa; and the bending blocks 9 and 10 are moved longitudinally towards each other through a. totaldistance of 0.028 inch, which is 200% of, the thickness of strip So.

When these two bent blanks are placed in nested relation, with the shorter base of the secwhen assembled as shown in Fig. 5 or elsewherein said application Serial No. 149,993, or the individual laminations may be separately annealed. The laminations are thus annealed while they are in final bent shape, such as the shape shown in said prior applications.

The blanks can be bent at ordinary room temperature of 20 C.-25 C. The blanks are preferably of equal width throughout. The invention applies to the shaping of blanks so as to provide them with one or more angles, and such blanks need not be of equal width or thickness.

When a set of blanks is in the nested formation shown in Fig. 5 of application Serial No. 149,993, the difference in height of the lateral legs of successive blanks may be equal to the thickness of said blanks, as disclosed in said application Serial No. 149,993.

Also, the respective lengths of respective succeeding blanks may be selected, and the lengths of the legs may be selected, to directly form the nested blanks shown in Figs. 6 and 7 of application Serial No. 149,993 and elsewhere in said application.

I have disclosed a preferred embodiment of the improved method and machine, but numerous changes and omissions and additions can be made without departing from its scope.

The invention also includes steps and sub-combinations of the disclosure herein.

I claim:

1. Combination bending mechanism for bending a blank, said mechanism comprising a bending block which has a longitudinal blank-supporting face and a lateral bending face which has a junction with said blank-supporting face, said lateral bending face being inclined to said blank-supporting face, a blank-retaining arm, said blank-retaining arm extending longitudi nally laterally over said blank-supporting face and being spaced transversely from said blanksupporting face, said blank-retaining arm being located relative to said blank-supporting face to hold the respective part of the blank in substantial contacting relation with said blank-supporting face and said blank-retaining arm, an inner longitudinal supporting arm which is pivoted at its inner end to said blank-retaining arm by a pivot which is located longitudinally inwardly of said junction, said inner longitudinal supporting arm having a stop, an outer longitudinal bending arm whose inner end is pivoted to the outer end of said supporting arm, said bending arm having an outer bending end, a spring connected to said supporting arm and to said bending arm and biasing said bending arm to contact said stop, said blank-retaining arm having a transverse recess at said junction, said bending arm being transversely movable through said recess to wipe its bending end in a direction along said lateral bending face to press the respective part of the blank against said bending face, said blank-retaining arm having a rear transverse leg which is fixed to the rear face of said bending block, said leg providing a stop for the respective edge of the blank, said spring urging said bending arm towards said bending face when said bending end clears said junction.

2. Combination bending mechanism according to claim 1 in which said arms are movable to a position in which said bending end is located in said recess and at least apart of said bending end is located longitudinally inwardly of said junction and abuts said blank-supporting face when said bending arm abuts said stop of said supporting arm.

Y References'cited in the. file of thispatent UNITED STATES PATENTS Number Name 4 Date 519,527 Carroll May 8, 1894 960,910 Hazen June 7, 1910 1,434,470 Abramsen Nov. 7, 1922 1,552,416 Bingham Sept. 8, 1925 2,336,611 Hill et a1 Dec. 14, 1943 2,420,119 Boehm May 6, 1947 2,477,355 Walton. ,July 26, 1949 2,485,495 Kenny et a1. Oct. 18, 1949 2,486,220

Somerville Oct. 25, 1949 

